Conditionally blocking reproduction of content items

ABSTRACT

A reproduction device ( 200 ) is arranged to conditionally block the reproduction of a particular content item ( 324 ). The reproduction has a unit ( 202 ) to obtain a content reference identifier ( 330 ) identifying the particular content item ( 324 ) and a storage unit ( 204 ) for storing the content reference identifier ( 330 ). A resolution process regularly checks on the basis of the content reference identifier ( 330 ) whether the particular content item is scheduled to be available, e.g. is scheduled for broadcast. When the scheduled broadcast of the particular item has been established, a blocking unit ( 210 ) blocks the reproduction device for that scheduled broadcast.

The invention relates to a method of conditionally blocking reproductionof content items on a reproduction device.

The invention further relates to a method of providing blockinginformation for conditionally blocking reproduction of content items ona reproduction device.

The invention further relates to a reproduction device for conditionallyblocking reproduction of content items.

The invention further relates to a set-top box, to a television set andto a video recorder comprising such a reproduction device.

The invention further relates to a system for providing blockinginformation for conditionally blocking reproduction of content items ona reproduction device.

European Patent 963114 B1 describes a system wherein content items,there called programs or portions of programs, can be blocked on thebasis of a viewing profile. In this system, a source signal carries thecontent items to be viewed at the subscriber's location. In addition tothe content item, the source signal contains an embedded contentidentifier describing a certain aspect of that content item. Examples ofsuch aspects are the type of the content item and the suitability of thecontent item being viewed by children. At the subscriber's location, thecontent identifier is compared with the viewing profile and on the basisof this comparison the reproduction of the content item is blocked ornot. The viewing profile can be used for parental control because aparent can prohibit children from viewing programs that are regardedunsuitable. The system relies on the co-operation of the broadcaster toembed the content identifier in the program. Furthermore, the value ofthe content identifier for a specific content item is determined by oron behalf of the broadcaster. This is subject to the broadcaster'sinterpretation of the content item and to the broadcaster's appreciationof what is suitable for children and what not.

It is an object of the invention to provide a method of conditionallyblocking reproduction of content items on a reproduction deviceproviding a more flexible control of blocking a content item. Thisobject is achieved according to the invention in a method comprising:

obtaining a content reference identifier for a particular content itemto be blocked,

-   -   resolving the content reference identifier into a locator        indicating availability of the particular content item, and    -   blocking the reproduction device for the indicated availability.

By using a content reference identifier for a content item to beblocked, blocking of reproduction of the content item can be effectedwithout having to rely on the co-operation of the broadcaster fortransmitting an indication along with the content item. The contentreference identifier, identifying the content item, can be obtainedusing another mechanism than the one for obtaining the content itemitself. This means that the information that a content item is to beblocked is provided in a different way than the content item. Thisallows for example that, prior to providing the content item, it isindicated that the reproduction of a content item is to be blocked.Indicating that the reproduction is to be blocked may be given even sofar ahead that it is not yet known when the content item is scheduled tobe provided. In that case, the content reference identifier for theparticular content item is simply stored and at regular times it ischecked whether the schedule has become known. As soon as it has becomeknown, the reproduction device is programmed to be blocked accordingly.

It is to be noted that the content identifier used in the system knownfrom European Patent 963114 B1 is fundamentally different from thecontent reference identifier according to the invention. The knowncontent identifier in European Patent 963114 B1 describes a certainproperty of the content item, for example the suitability of the contentitem being watched by children. An example of the know contentidentifier is “PG 13”, indicating that a parent should be present if thecontent item is watched by children younger than 13. The contentreference identifier according to the invention only identifies thecontent item and does not describe a certain property of the contentitem. The content reference identifier according to the inventionprovides an identification, which makes it possible, that differentparties refer to this one content item. An example of the contentreference identifier is “Alien”, referring to a content item that is themovie called Alien.

An embodiment of the method according to the invention is described inclaim 2. The invention can advantageously be applied in a broadcastenvironment, where a broadcaster transmits radio and TV programsaccording to a given schedule. At some moment, the user of thereproduction device, e.g. the television or the set-top box, maydetermine the existence of a particular content item that he regardsunsuitable to be reproduced on his reproduction device. The user thenobtains the content reference identifier for that content item andstores it in the reproduction device thereby indicating thatreproduction of that item is to be blocked. Some time after storing thecontent reference identifier in the reproduction device, this contentreference identifier is resolved, i.e. translated, into informationrelated to the broadcast schedule. Then it becomes known when and atwhich channel the content item will be broadcast and the reproductiondevice is programmed to be blocked accordingly.

An embodiment of the method according to the invention is described inclaim 3. In such an environment, where content items are retrieved onthe initiative of the user rather then broadcast on the initiative ofthe broadcaster as in the broadcast environment, the invention can alsobe applied advantageously. An example of such an environment is avideo-on-demand server where a video program is transmitted to a user'sreproduction device on the request of the user. Another example is anInternet server comprising various content items, e.g. video clips thatmay be selected for downloading to, or reproduction on, the reproductiondevice. In this embodiment, the content reference identifier is resolvedinto the name of the providing server and the period during which theserver keeps the particular content item available for retrieval. Afterresolution of the content reference identifier, the reproduction deviceis programmed to be blocked for retrieval of the particular content itemfrom the named server for the indicated period.

An embodiment of the method according to the invention is described inclaim 4. In this embodiment, an authorized user may overrule theblocking of the reproduction device. This may be used for parentalguidance, where the reproduction device is blocked to prevent a childwatching a particular content item on its own, but where the parent canoverrule the blocking to be able to watch the content item.

An embodiment of the method according to the invention is described inclaim 6. A further advantage of providing the information thatreproduction of a content item is to be blocked separate from providingthe content item is, that the information may be obtained from adifferent party than the party providing the content item. The user ofthe reproduction device may want to use the advice concerning blockingcertain contain items from that party, e.g. because the user trusts theopinion of that party regarding the suitability of content items forchildren. Such party may be a school organization, a consumerorganization, a religious organization, or other organization thatpromotes certain ethic values. The organization may host a websiteoffering various blocking lists. Textual descriptions can inform theuser about the purpose of each of the lists. The user can select a listto transmit the content reference identifiers to the reproductiondevice.

An embodiment of the method according to the invention is described inclaim 7. This embodiment provides an easy and simple mechanism for theuser to obtain the content reference identifier for the particular item.Here, the content reference identifier of the particular item is sent tothe reproduction device during reproduction of another content item. Anexample is that during reproduction of a commercial announcing ordescribing the particular content item, the content reference identifierof the particular content item is available in the signal. The user isgiven the option to indicate that reproduction of the particular contentitem should be blocked and if the user does so, the content referenceidentifier is stored in the reproduction device. Another example is thatin the trailer of a movie, a later movie is announced and the contentreference identifier for the later movie is embedded in the signal. Theuser seeing the announcement of the later movie decides that this movieis not suitable for reproduction on the user's reproduction device andindicates such, for example by pressing a reject button on the remotecontrol. In practice, the term trailer is not only used forannouncements literally trailing a program but the term is also used fora general program announcement.

It is a further object of the invention to provide a method of providingblocking information for conditionally blocking reproduction of contentitems on a reproduction device allowing a more flexible control ofblocking a content item. This object is achieved according to theinvention in a method comprising:

-   -   preparing an advisory list containing a reference to a        particular content item and containing a content reference        identifier for that particular content item, and    -   making the advisory list available for transfer to and use in        the reproduction device for        -   resolving the content reference identifier into a locator            indicating availability of the particular content item, and        -   blocking the reproduction device for the indicated            availability.

This method according to the invention makes it possible to provideblocking information for a particular content item separate fromproviding the content item itself. Thus the blocking information about acontent item can then easily be assembled and provided by a differentparty than the party providing the content item.

It is a further object of the invention to provide a reproduction devicefor conditionally blocking reproduction of content items with a moreflexible control of blocking a content item. This object is achieved ina reproduction device comprising:

-   -   obtaining means for obtaining a content reference identifier for        a particular content item to be blocked,    -   receiving means for receiving the result of resolving the        content reference identifier into a locator indicating        availability of the particular content item, and    -   blocking means for blocking the reproduction device for the        indicated availability.

In the reproduction device according to the invention, the informationthat reproduction of the particular content is to be blocked may bereceived separately from the content item itself. The blockinginformation can be obtained as soon as the user is aware of theparticular content item and prior to the content item itself becomingavailable. The blocking information is received in the form of thecontent reference identifier and may be stored in the device for laterresolution. The resolution may be done external to the reproductiondevice and when the device receives the resolution result, indicatingthe availability of the particular content item, the device isprogrammed to be blocked accordingly.

An embodiment of the reproduction device according to the invention isdescribed in claim 12. Since this reproduction device is able to resolvethe content reference identifier internally, it does not need anexternal service for obtaining the locator information. To this end, thereproduction device receives resolution information enabling theresolution of the content reference identifier into the locator. Anexample of this is that the reproduction device receives the contentitems in a channel of a DVB transport stream and that the resolutioninformation is sent in a data stream of the DVB transport stream.

The system according to the invention for providing blocking informationfor conditionally blocking reproduction of content items on areproduction device comprises:

-   -   preparation means for preparing an advisory list containing a        reference to a particular content item and containing a content        reference identifier for that particular content item, and    -   managing means for making the advisory list available for        transfer to and use in the reproduction device for        -   resolving the content reference identifier into a locator            indicating availability of the particular content item, and        -   blocking the reproduction device for the indicated            availability.

The invention and its attendant advantages will be further elucidatedwith the aid of exemplary embodiments and the accompanying schematicdrawings, wherein:

FIG. 1 shows an overview of the operation of the invention,

FIG. 2 schematically shows the most important components of areproduction device according to the invention,

FIG. 3 schematically shows a system for providing blocking informationaccording to the invention,

FIG. 4 schematically shows a set-top box according to the invention,

FIG. 5 schematically shows a television according to the invention, and

FIG. 6 schematically shows a video recorder according to the invention.

Corresponding features in the various Figures are denoted by the samereference symbols.

FIG. 1 shows an overview of the operation of the invention. Theinvention uses the concept of a content reference identifier. Thiscontent reference identifier or CRID uniquely identifies each individualcontent item. The CRID does not identify a particular broadcast of acontent item like a program, but identifies the program as such.Therefore a repeat of a program will usually have the same CRID as theoriginal broadcasting. The CRID for a program resembles the ISBN(International Standard Book Number) for a book, since the ISBN alsouniquely identifies the book. The CRID is not limited to broadcasttransmissions of content items. It could also be used to identifycontent items available on the Internet or any other source. When theCRID of a specific content item has been obtained by the user, the nextstep is to resolve the CRID into a locator indicating when and where thecontent item will be available. In the broadcast environment, thelocator is the scheduled broadcast of the program indicating the timeand channel of broadcast. One can search for content items like moviesand obtain CRIDs for the content items while the broadcast details ofthe movies are not yet known.

The concept of content reference identifier is also of interest forrecording of programs. For example a user may want to record an episodeof a television series, but he does not necessarily know when and wherethat episode will become available. He can then use his personal digitalrecorder (PDR) or similar device to enter a reference to the episode orseries by means of the CRID. Note that a CRID may refer to an entireseries or to an individual episode thereof or even to a segment of anepisode. Having received a CRID for a content item, the PDR tries toobtain the location of the content item. This information is called alocator and it contains the date, time and channel on which the contentitem will be broadcast. The user however does not need to be aware ofthis. Once the PDR has obtained the locator of the content item, the PDRwaits for the specified date and time and then records the episode as itis broadcast on the specified channel. Of course, if the locatorindicates a location on the Internet or the like, the PDR can simplyretrieve the content from the indicated location as soon as it becomesavailable.

In the context of recording of programs, the TV-Anytime standardizationbody provides a standardized Content Reference ID. See TV-Anytime Forum,www.tv-anytime.org, Specification Series: S-4, on Content Referencing(Normative), Document SP004V11, 14 Apr. 2001.

The syntax of the CRID as used by TV-Anytime is as follows:CRID://<authority>/<data>

The <authority> field indicates the body that created the CRID. Anauthority will also provide the ability for the CRID to be resolved intolocators or other CRIDs. A locator is the name for locations in time andspace of content. The <data> field is a free format string that iscompliant with the definition of Uniform Resource Identifiers (URIs) asgiven in RFC 2396. This string should be meaningful to the authoritygiven by the <authority> field.

The CRID is used for location resolution, which can be defined as theprocess of translating a CRID into other CRID(s) or locators. Forinstance, a CRID for an entire TV series could be translated into aseries of CRIDs for the individual episodes of that series. Locationresolution may be done in the recording device (typically a PersonalDigital Recorder or PDR) or remotely. A resolution provider doeslocation resolution. Resolution providers use resolving authorityrecords (RARs) to be identified and located. A RAR includes at least an<authority> field, corresponding to a body that creates CRIDs.

A RAR also contains a URL and the resolution provider name. The URLpoints to the location where resolution information can be found. Theresolution provider name contains the name of the body that is providinglocation resolution. These RARs are made available to PDRs.

The CRID for the content item is used to facilitate automatic recordingof the content item. The CRID could be entered manually by the user, orbe the result of selecting a content item through an Electronic ProgramGuide. This second option assumes that the CRID is somehow provided tothe PDR together with other metadata used in the EPG. Alternatively, ifthe CRID is not known by the user or by the PDR, the user could performa search using for example the title of the content item in a metadatadatabase, and select the desired content item from the search results.The CRID is then supplied to the PDR by the search engine.

There are many other ways to provide the CRID to the PDR. For example, atrailer or preview for a movie could be broadcast with the CRID embeddedin the content of the commercial in some way (e.g. a watermark). Theuser could then press a button on his remote control, television or PDR.The PDR or television then extracts the CRID from the content.

Once the CRID for the content item is known, the PDR tries to obtainlocator information for the content item, using the CRID as input. Thislocator information is not necessarily always available. For example,the CRID may refer to a movie that has only recently been released inmovie theaters. This movie is not likely to be broadcast on televisionin the near future, so it cannot be scheduled using EPG information. Insuch a case, the PDR should regularly try to obtain the locator, as thelocator may become available later (e.g. a year later, when the movie isgoing to be broadcast on TV). The CRID could also refer to a TV series,which is then resolved into a number of CRIDs for individual episodes ofthat series. It is possible that no locator information is available forsome episodes. Here the PDR should also regularly retry to obtain thelocator(s) for those episodes.

The process of translating a CRID into other CRIDs or locators is knownin TV-Anytime as location resolution. Location resolution involvesmapping a location-independent content reference (the CRID) to itslocation in time (e.g. scheduled transmission time in a broadcastsystem) and space (e.g. TV channel, IP address). As explained above,these locations in time and space are referred to as “locators.” Theprocess of location resolution may happen inside the PDR or by using aphysically remote server, such as a server on the Internet.

To the PDR, the CRID essentially contains opaque information, which itcannot resolve to a location without external assistance. A ResolutionProvider (RP) who provides locator information for CRIDs is provided tosolve this problem. Usually multiple RPs are available, and the PDR mustknow which RP to use for a particular CRID. Often, this is the same bodythat created the CRID. The name of the authority is present in the CRIDin the <authority> field, as explained above. This name is present inthe form of a registered Internet domain name. It is possible for aResolution Authority (RA) to be found on the Internet using the domainname resolution process specified in the TV-Anytime specification SP004.

Each RA will require one or more Resolving Authority Records (RAR) toexist in the PDR for location resolution to take place. Each resolvingauthority record will need to be placed inside some sort of transportspecific container that allows the PDR to know that this is a RAR. Inthe case of multiple records for the same authority, the PDR can chooseto just use one of them, or try them all in turn. The ResolvingAuthority Record (RAR) contains the information that identifies the RAand the RPs where content reference resolution information can be found.

Using the RAR, the PDR determines which RP to use to resolve aparticular CRID. The PDR then submits a request for a locationaccompanied by a CRID to the Resolution Provider in question. Inresponse to this request, the Resolution Provider returns the locatorinformation (assuming this information is available in that RP, ofcourse). The PDR can then access the content source and obtain thecontent item. A content item may have more than one locator, for exampleif it is broadcast multiple times or available from multiple providers.The PDR may then choose which locator to use, or prompt the user to makea selection.

Once the locator information has been obtained, the PDR waits for thespecified date and time and then records the episode as it is broadcaston the specified channel. Of course, if the locator indicates a locationon the Internet or the like, the PDR can simply retrieve the contentfrom the indicated location as soon as it becomes available.

The overview of FIG. 1 shows the various parties involved for thepresent invention. The invention uses the CRID explained above forreferring to content items. There is a broadcaster 102 who transmits asignal 104 containing TV-based content items like talk shows, movies,episodes of a series and the like. The signal 104 is received by atelevision set 106 at a subscriber's location. The transmissionmechanism between the broadcaster and the user's location is notrelevant to the invention. The transmission channel may be a satellitelink whereby the signal is received at the user's location, or asatellite link to a head end and a cable connection between the head endand the user's location, or a terrestrial broadcast or any othersuitable mechanism. The transmission may be carried out in digital form,for example according to the Digital Video Broadcast standard, but mayalso be in analog form. Instead of a television set, the signal may bereceived by a so-called set-top box. Such a set-top box processes thereceived signal, e.g. descrambles and decodes the signal, so that it maybe displayed on a simple display device. Furthermore, there is a CRIDprovider 108 providing CRIDs for the various content items. For thepurpose of explaining the invention, the CRID provider is regarded as asingle party, but providing a new CRID may be done by different partiesand in a hierarchical way. For example, the may be one central party whodefines CRIDs at the highest level and who provides ranges of CRIDs tobe further filled in by a party like a broadcaster. Nevertheless, forunderstanding the present invention it suffices to know that a CRIDexists to refer to a particular content item. According to theinvention, the CRID is used to refer to a content item that should beblocked by the user's television set 106, i.e. the television set shouldblock the reproduction of that content item. Given a particular CRID,the next step is to determine when the content item will be broadcast.As described above, this process is called resolution. The ResolutionProvider 110 provides on request the scheduled time and channel of theparticular CRID. The Resolution Provider operates closely with thebroadcaster, since it is the broadcaster who determines the schedule.Often, the broadcaster provides the role of resolution provider. Thus,when a user becomes aware of a content item that should be blocked bythe television set, the user obtains a CRID and stores this in thetelevision set. The television then regularly checks whether the contentitem is scheduled for broadcast and if so, the television blocks itselffor the indicated channel and time. The CRID preferably remains storedin the television set to allow continued checking of further broadcastsof the content item.

There are various ways through which a user may obtain a CRID and storeit in the television set. A very simple way is where the CRID of acontent item is printed, e.g. in a newspaper with review of that contentitem, and where the television set has a user interface for entering theCRID. The user then selects a specific blocking registration function ofthe television and manually enters the CRID into the television set. Theuser interface may be realized through menus in an On Screen Display,i.e. menus displayed on the television, and the keys of the remotecontrol or other keyboard. Another way is to embed the CRID of aparticular content item during a certain period in the signal 104broadcast to the television set and to allow the user during this periodto indicate that the CRID must be stored. Examples of techniques toembed the CRID are to code the CRID in one or more lines of the VerticalBlanking Interval (VBI) of an analog television signal or transport theCRID via a data channel in the case of a digital transmission as DVB. Anadvantageous implementation of this way of providing the CRD) to theuser is the following. In a certain commercial, a particular movie isadvertised and during this commercial the CRID of the movie is presentin the signal 104. The user is made aware of this presence, e.g. througha notification on the display. If the user decides that he wants toblock his television for future broadcasts of the movie, he may simplypress a designated key, the block key, on his remote control. Then thetelevision retrieves the CRID from the signal and stores it for laterblocking as described above. Alternative to a commercial for aparticular movie, the same mechanism can be used in a show where variousmovies or other programs are presented and reviewed by the presenter ora panel or the like. A still further way through which a user may obtaina CRID is with the help of a party who provides advice regarding thesuitability of content items and who provides the corresponding CRIDs.This party, referred to as blocking advisor 111, collects informationabout content items that come available and their corresponding CRIDS,e.g. from the CRID provider 108. Furthermore, the blocking advisor formsan opinion about the suitability of the content item for certain groupsof viewers. The blocking advisor may do so on the basis of personallyviewing the content items or on the basis of reviews and critics fromother parties. The blocking advisor categorizes the content items intolists corresponding with their suitability, e.g. a list with contentitems to be blocked for children under 6, a list with content items tobe blocked for children under 12, under 16, etc. Additionally oralternatively, the lists may be based on the reasons as to why thecontent items are regarded unsuitable, e.g. a list with content items tobe blocked because of the presence of too much violence, a list withcontent items to be blocked because of the presence of sex, because ofthe presence of blasphemy, etc. The user of television set 106 selects alist with content items to be blocked from the available lists at theblocking advisor 111 and retrieves the CRIDs associated with that listvia a connection 112. This connection 112 can be an Internet connectionthrough which the user may browse the site of the blocking advisor 111and download the CRIDs.

FIG. 2 schematically shows the most important components of areproduction device according to the invention. The reproduction device200 has an obtaining unit 202 for obtaining one or more CRIDs of contentitems that are to be blocked. These CRIDs are stored in CRID storageunit 204 from where they will be used regularly to check theavailability of the content items that they identify, i.e. they areregularly used for content resolution. The reproduction device 200optionally has a resolution unit 206 to perform this content resolution.The result of the content resolution, this is a so-called locatorindicating the scheduled availability of the content item, is stored inlocator storage unit 208. If the reproduction device has no resolutionunit of its own, it can request external content resolution on the basisof its stored CRIDs via connection 209 and receives the locators inlocator storage unit 208. A blocking unit 210 checks the locator storageunit to determine whether blocking needs currently to be done. To thisend, blocking unit 210 receives information regarding the currentchannel and time via connection 212. If blocking needs to be done, theblocking unit sends a blocking signal indicating this back viaconnection 212. Alternatively to receiving the current time viaconnection 212, the blocking unit may determine the current time from aninternal clock. The reproduction device 200 optionally has an overridingunit 214 that is able to override the blocking unit 210. If theoverriding unit 214 receives a proper authorization signal 216 itoverrides any blocking set by the overriding unit. In this way, thereproduction of a content item will be effected, even if based on thestored CRID reproduction should be blocked. Such mechanism can be usedfor parental control where only the parent can provide the properauthorization signal 216. The authorization signal 216 may be determinedon the basis of an authentication technology that is known per se.Examples of such authentication technology are: a password, smart cardwith a key, finger print recognition and voice recognition. Thereproduction device 200 is implemented according to a known computerarchitecture. The various units are implemented as software componentswith instructions that are loaded into the working memory of the device.A processor of the device executes the instructions to perform thefunctions of these components. Alternatively, the reproduction devicemay be implemented by means of dedicated hardware components.

FIG. 3 schematically shows a system for providing blocking informationaccording to the invention. This system is arranged to provide this asCRIDs to reproduction devices as described above. The system isimplemented on a general-purpose computer 302, like a personal computer,according to a known architecture. The various functions of the systemin this embodiment are realized in respective software components asdescribed below. This is an exemplary embodiment and another way ofmapping the functions onto units is also feasible. The system has aworking memory 304 into which the various software units are loaded forexecution. The further structure for executing and controlling operationof the computer is not shown in FIG. 3. The computer has an interface306 for communicating with the peripheral devices. The system has adisplay device 308 on which the images are displayed. Furthermore, thesystem has input devices, like keyboard 310 and mouse 312, with which auser can enter commands and data. The system has a storage device 314 onwhich software components, advisory lists with CRIDs, and other data maybe stored. This storage device is a magnetic disk drive but othersuitable storage devices may be used. Furthermore, the system has anetwork connection 316 for connecting to a network, like the Internet.The system has a preparation unit 318 that prepares the advisory lists,e.g. the advisory list 320 shown in the figure. The advisory list 320refers to a number of content items 322, 324 and 326 indicating thatreproduction of these content items is advised to be blocked. It is tobe noted that these content items themselves are not stored in thesystem. The advisory list 320 only refers to the content items 322, 324and 326. To this end, the advisory list 320 contains respective CRIDs328, 330 and 332. The system 300 further contains a managing unit 334that makes the stored advisory list available to be accessed. A user ofa reproduction device may connect to the system through networkconnection 316 and browse through the advisory lists stored on storagedevice 314. Upon selecting a specific advisory lists, the CRIDs of thisselected lists are downloaded via the network connection 316 and storedin the user's reproduction device. There, the CRIDs are used forcontrolling blocking the reproduction device as described above.

FIG. 4 schematically shows a set-top box according to the invention. Theset-top box 400 contains a receiver 402 for receiving content items viaan input 404. The content items can be transmitted to the set-top box inone of various way, as described in connection with FIG. 1. The receivedcontent items are processed in the set-top box with a processing unit406 and subsequently sent out via output 408, e.g. for display orrecording. The set-top box 400 further contains a reproduction device200 as described above. The reproduction device may receive CRIDs fromthe receiver 402 or via an input 410, which may either for manual entryor retrieval through a network. The reproduction device controls theprocessing unit 406 for blocking the processing of certain content itemson the basis of stored CRIDs.

FIG. 5 schematically shows a television according to the invention. Thetelevision 500 contains a receiver 502 for receiving content items viaan input 504. The content items can be transmitted to the television inone of various way, as described in connection with FIG. 1. The receivedcontent items are processed in the television with a processing unit 506to be displayed on a display device 508, e.g. a CRT. The television 500further contains a reproduction device 200 as described above. Thereproduction device may receive CRIDs from the receiver 502 or via aninput 510, which may be done either through manual entry or throughretrieval via a network. The reproduction device controls the processingunit 506 for blocking the display of certain content items on the basisof stored CRIDs.

FIG. 6 schematically shows a video recorder according to the invention.The video recorder 600 contains a receiver 602 for receiving contentitems via an input 604. The content items can be transmitted to thevideo recorder in one of various way, as described in connection withFIG. 1. The video recorder 600 contains a reproduction device 200 asdescribed above. The reproduction device may receive CRIDs from thereceiver 602 or via an input 610, which may be either via manual entryor via retrieval through a network. The reproduction device checkswhether reproduction of the received content items is to be blocked andprovides a corresponding blocking signal as described in connection withFIG. 2. The video recorder 600 has a storing unit 605 for storing thecontent items and if present the blocking signal on a storage medium606. This storage medium 606 is a hard disk, but other suitable medialike a CD-RW may be used. Furthermore, the video recorder 600 has aretrieving unit 608 for retrieving a stored content item from thestorage medium 606. This is only allowed if no blocking signal has beenstored for this content item, i.e. it is only allowed if thereproduction device 200 had established that no blocking was requiredfor this content item. If blocking was required and there is suchblocking signal, than a special authorization is required in order toactivate the retrieving unit. To this end, the video recorder containsan overriding unit as described in connection with FIG. 2. The contentitems retrieved from the storage medium are processed and subsequentlysent out via output 612, e.g. for display or recording.

It should be noted that the above-mentioned embodiments illustraterather than limit the invention and that those skilled in the art willbe able to design many alternative embodiments without departing fromthe scope of the appended claims. In the claims, any reference signsplaced between parentheses shall not be construed as limiting the claim.The word ‘comprising’ does not exclude the presence of elements or stepsother than those listed in a claim. The word “a” or “an” preceding anelement does not exclude the presence of a plurality of such elements.The invention can be implemented by means of hardware comprising severaldistinct elements and by means of a suitably programmed computer. In theunit claims enumerating several means, several of these means can beembodied by one and the same item of hardware.

1. A method of conditionally blocking reproduction of content items on areproduction device, the method comprising: obtaining a contentreference identifier for a particular content item to be blocked,resolving the content reference identifier into a locator indicatingavailability of the particular content item, and blocking thereproduction device for the indicated availability.
 2. A method asclaimed in claim 1, wherein the content items are broadcast and thereproduction device is arranged to receive broadcast content items,wherein the locator indicates a scheduled broadcast of the particularcontent item at a specific time on a specific channel, and wherein thereproduction device is blocked for reproduction for the specific timeand channel.
 3. A method as claimed in claim 1, wherein the contentitems reside on a server available for transfer on a request from thereproduction device, wherein the locator indicates the availability ofthe content item at the server during a specific period of time, andwherein the reproduction device is blocked for retrieval of the contentitem from the server for the specific period of time.
 4. A method asclaimed in claim 1, wherein blocking of the reproduction device isreversed by a user with a proper authorization.
 5. A method as claimedin claim 4, wherein the proper authorization is determined by at leastone of: entry of a password, entry of a smart card, recognition of afinger print, and voice recognition.
 6. A method as claimed in claim 1,wherein obtaining the content reference identifier of the particularitem includes: selecting from an external location an advisory listcontaining at least a reference to the particular content item, andreceiving content reference identifiers for the content items referredto on the list.
 7. A method as claimed in claim 1, wherein obtaining thecontent reference identifier of the particular item includes: receivinga signal representing a further content item and containing the contentreference identifier, during reproduction of the further content itemenabling a user to indicate storing the content reference identifier,upon the user so indicating, storing the content reference identifier.8. A method of providing blocking information for conditionally blockingreproduction of content items on a reproduction device, the methodcomprising: preparing an advisory list containing a reference to aparticular content item and containing a content reference identifierfor that particular content item, and making the advisory list availablefor transfer to and use in the reproduction device for resolving thecontent reference identifier into a locator indicating availability ofthe particular content item, and blocking the reproduction device forthe indicated availability.
 9. A method as claimed in claim 8, whereinthe advisory list is stored on a server, and wherein a user is enabledfor selecting the list for transfer to the reproduction device.
 10. Amethod as claimed in claim 8, wherein the advisory list is broadcast tothe reproduction device and wherein the user is enabled to indicatestoring the advisory list in the reproduction device.
 11. A reproductiondevice for conditionally blocking reproduction of content items, thedevice comprising: obtaining means for obtaining a content referenceidentifier for a particular content item to be blocked, receiving meansfor receiving the result of resolving the content reference identifierinto a locator indicating availability of the particular content item,and blocking means for blocking the reproduction device for theindicated availability.
 12. A reproduction device as claimed in claim11, wherein the reproduction device comprises resolution means forresolving the content reference identifier into the locator and whereinthe receiving means are arranged to receive the result from theresolution means.
 13. A set-top box for reproducing content itemscomprising: a receiver for receiving the content items, and areproduction device for conditionally blocking reproduction of one ormore content items as claimed in claim
 11. 14. A television set forreproducing content items comprising: a receiver for receiving thecontent items, a reproduction device for conditionally blockingreproduction of one or more content items as claimed in claim 11, and adisplay for displaying the content items not blocked by the reproductiondevice.
 15. A video recorder for storing and reproducing content itemscomprising: a receiver for receiving the content items, a reproductiondevice for indicating conditionally blocking of reproduction of one ormore content items as claimed in claim 11, storing means for storing thecontent items on a storage medium, and retrieving means for retrievingthe content items from the storage medium.
 16. A system for providingblocking information for conditionally blocking reproduction of contentitems on a reproduction device, the system comprising: preparation meansfor preparing an advisory list containing a reference to a particularcontent item and containing a content reference identifier for thatparticular content item, and managing means for making the advisory listavailable for transfer to and use in the reproduction device forresolving the content reference identifier into a locator indicatingavailability of the particular content item, and blocking thereproduction device for the indicated availability.